I was concerned about black growths on my rocks once as well but it turns out it was some type of sponge/coral. Are they soft but firm to the touch and rounded? I'm not sure about your live rock issue, I had a bunch bleach out on me when I put MH bulbs over them but they turned purple again after awhile. Are calcium/alk levels OK? Too long of a photoperiod or a change in lighting can change the coloring for awhile. If everything else in the tank is doing well and levels are OK all I can say is keep up with water changes and I'm sure the color will come back, sometimes very slowly.
|